Improved extension-ladder



UNITED STATES PATENT OFFICEo M. M. KNOWLES, OF ELMIRA, NEW YORK.

IMPROVED EXTENSION-LADDER.

Specification forming part of Letters Patent No. 81,279, dated August 18, 1868.

To all whom it may concern Be it known that I, M. M. KNOWLES, of the city of Elmira, in the county of Ghemung and State ot' New York, have invented a new and useful Improvement in Extension cr Step- Ladders; and I do hereby declare that the following is a full, clear, and exact description ot' the construction and operation of the same, reference being had to the annexed drawings, making part of this specification,

in Which- Figure 1 is a perspective as a ladder. Fig. 2 is a section ot' the same. Fig. 3 is a perspective View of the same when extended. Fig. 4 is an inverted view of the same when extended. Fig.5 is a section 0f ladder when extended. Fig. 6 is a plan of brace, and Fig. 7 is a side elevation of brace.

The nature of'my invention consists in so constructing a ladder that it may be readily changed from a step-ladder to an extensionladder, and secured firmly in either position, fitting it for a house or fruit ladder.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

I construct a ladder with steps at suitable distances, similar to those in general use, with curved tapering legs or sides A A B B to sustainitself. Brace F D, Figs. 1, 2, holds ladder iirm and prevents it from closing, while cords H H prevent it from spreading, and are attached to extension B B, with hooks at the opposite ends. These cords are crossed and hooked into staples M, provided on legs A A. It can be extended so as to form a long and substantial ladder. This extension part B is hinged on the inside of legs A B with suitable hinges, G, Figs. 1, 2, 3, 6, 7, and when extended, as shown iu Figs. 3, 4, it is held in position firmly by brace D F, Figs. 6, 7.

We will suppose the ladder to be extended,

being held firm by brace D F, Figs. 3, 4. It can then be moved from place to place without closing. It may be changed and used as a step-ladder by loosing thumb-screw J, Fig. 4, and relieving brace D F; then turning extension B B down on the back part of main steps A A, forming the legs of step-ladder. The brace D F being placed on pin I, Figs. 1, 3, holds it firm and preventsit giving one Way, an'd the cords `lI l-I, hooked in their places, hold it the other, as described, and allow the step-ladder to be moved from place to place without closing.

The adjustable brace D F is so constructed as to answer two purposes-lirst, to hold the ladder firm when extended; secondly, to hold the legs in position and lock them at the same time, to form a self-supporting step-ladder. The adjustable brace D F is made in two partspiece F, Figs. 6, 7, having a slet, K, in it, the other part, D, having a thumbscrew, G, and serves to hold the two pieces firm to each other when set the length required, thus allowing the brace to be lengthened or shortened, as required. One end of brace D is hinged to extension B with suitable hinges, E, as shown in Figs. 2, 5, 6, 7. The end of brace F has a hole iu it that tits the pin I (shown in Figs. -1, 3) in the step of the main steps A A, thus making a tirm brace when properly adjusted.

What I claim,-and desire to secure by Letters Patent, is-

The combination of ladders A and B, adjustable brace D F, and pin J, all constructed and arranged substantially as described, as and for the purpose specited.

M. M. KNOVLES. 

